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Drugs lead to brain brake failure

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 A single dose of morphine was found to lower the inhibitions of rats, even after the drug had left their systems, a finding that may help scientists better understand addiction in humans, US researchers said.

In rats, the painkiller blocked the brain’s ability to strengthen connections, or synapses, that ratchet down reward or pleasure, researchers from Brown University reported in the journal Nature.

“What we have found is that the inhibitory synapses can no longer be strengthened 24 hours after treatment with morphine, which suggests that a natural brake has been removed,” said Julie Kauer, a professor of molecular pharmacology, physiology and biotechnology at Brown.

“This happens 24 hours after the animal had one dose of morphine. There is no morphine left in the brain. It shows that it is a persistent effect of the drug,” she said in a telephone interview.

Kauer said the finding adds to a growing body of evidence suggesting a link between learning and addiction and may help in the development of drugs to treat addiction. “Strengthening synapses, we think, is the beginning of the formation of memory,” she said.

By shutting off the natural ability to strengthen connections that inhibit pleasure, the brain may be learning to crave drugs, she said.

Kauer said the brain has two kinds of neurons  those that excite the nerve connections and those that inhibit or depress them.

“If inhibition is reduced, you get runaway excitability,” she said. This imbalance may boost the firing of neurons that make dopamine, the brain’s “pleasure chemical” activated after rewarding experiences such as eating, sex, and the use of addictive drugs.

Kauer found the changes in a small section of the midbrain that is involved in the reward system. While her study looked at the early response to addictive drugs, she intends to study the effect over time.

Source:The Times Of India

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A ray of hope for autism.

After years of research, scientists have zeroed in on the genes responsible for autism. V. Kumara Swamy reports

A five-year-long international study that looked into the genetic underpinnings of autism has zeroed in on new genes, giving hope to millions that some day a treatment for this complex brain disorder may be possible. According to current estimates, around 1.7 million people suffer from autism in India.


The preliminary results of the study, gleaned from a large sample of 1,200 families with multiple cases of autism in 19 different countries, were published in this month’s issue of Nature Genetics. More than 120 scientists from 50 institutes participated in the exercise.

The Autism Genome Project, launched way back in 2002, in its first phase assembled the largest gene “biobank” in the world. It conducted a comprehensive genome scan, announcing last month that the susceptible genes  responsible for inheriting the risk of the disease  have been identified.

Autism is a psychiatric disorder that inhibits a child’s ability to communicate and develop social relationships, resulting in slow learning and severe intellectual impairment in some cases.

The identification of the susceptible genes, say the experts, will provide an insight into the basis of the disease as well as pave the way for developing intervention methods.

The scientists had at their disposal a gene chip  technology that can rapidly look for genetic commonality in the samples collected.

The new study implicates a previously unidentified region of chromosome 11 and neurexin 1, a member of a family of genes believed to be important in neuronal contact with and communication to other parts of the body. Although there have been several genetic analyses for autism, the results have not been uniform and none has been performed on such a large scale before.

Researchers also speculate that there may be five or six major genes and as many as 30 others involved in autism. If a foetus has more of these genes, there is a higher chance of being born with autism or a more severe form of the disease.

According to Andy Shih of Autism Speaks, a New York-based organisation, the findings could have an impact in the near future. Some of the data will have immediate diagnostic impact, and the new understanding of the genetic contributors will give direction to the development of targeted treatment and intervention,  he says. Shih’s organisation is one of the funders of the current research study.

First classified as a specific disorder over 50 years ago, the incidence of autism is rising steadily, although the criteria for diagnosis have changed over time.

There have been various estimates for autism in India, but no prevalent study that can arrive at a definite figure, says Dr Shobha Srinath of the National Institute of Mental Health and Neuro Sciences (Nimhans), Bangalore. Moreover, there may be underreporting in many places owing to ignorance, she adds.

While it is estimated that one in every 500 children suffer from autism in India, in countries like the US, the problem is more acute with the figure being one in every 150 children. According to experts, the disease affects more boys than girls. In the UK, autism is said to affect one in every 100 children.

Researchers have for long suspected a genetic link to the disease, and the latest study only confirms that, says Dr J.R. Ram, consultant psychiatrist, Apollo Gleneagles Hospital, Calcutta. “The study is a breakthrough so far as understanding the problem is concerned, but because autism is such a complex disease we need to be realistic about the findings,” he adds.

Parents, it seems, are also of the same opinion.  see this study as a ray of hope, but I think we are still some distance away from any effective treatment in the form of medication,” says Indrani Basu, the parent of an autistic child and also the head of the Autism Society of West Bengal, Calcutta.
Source:The Telegraph (Kolkata,India)

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Sleep well to remember well

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Grey regions of the brain    talk to each other during deep sleep to produce great memory. T.V. Jayan on some recent findings:……....CLICK & SEE

Staying up all night studying does more harm than good  it leads to fuzzy memories the next day. In other words, our mental scrapbook’s ability to register fresh memories is seriously compromised if a good night’s sleep is denied, scientists say.

Neuroscientists have known for a while that sleep deprivation does hamper the consolidation of long-term memory    the exact mechanism of which  was unraveled recently by an India-born scientist and his colleagues in the US and Germany. But now a team of researchers from Harvard Medical School, Boston, has shown that lack of sleep not only fetters memory retention but also its very formation.

Matthew Walker and co-workers at the Harvard centre reported on February 11 in the online version of Nature Neuroscience that sleep before learning is crucial to preparing the brain for the next day’s memory formation. The findings, they say, are  worrying   considering society’s increasing erosion of sleep time.

The Harvard scientists scanned the brain’s hippocampus region   where everyday events are minted into fresh memories    using sophisticated functional Magnetic Resonance Imaging (fMRI)‘ technique. The study involved 28 volunteers in the age group of 18-30 years. The individuals were divided into two groups, with one made to stay awake for nearly 35 hours (two days and one night), and the other permitted to have a normal night’s sleep. The group that kept up was allowed to read books, take short walks, surf or chat on the Internet or play board games.

Towards the end of the second day, all participants were shown a slideshow of 150 pictures of landscapes, objects and non-celebrities. As they watched, their brains were mapped using fMRI. The scientists found that the mean recognition levels of the sleep-deprived group were about 20 per cent less than that of the other. The participants were then recalled after a full day’s break and asked to identify the slides they had earlier seen as a set of 75 fresh slides were added to the lot.  The volunteers who lacked sleep on the first day performed poorly, despite having had two nights to recover the lost sleep, the scientists said.

Your ability to learn is 20-40 per cent worse, that is, the difference between acing the exam and failing it miserably,  Walker told Know How.

While the work done by Walker and his associates conclusively proved that sleep before learning is vital, scientists had little clue about the brain mechanisms that help sleep to move and consolidate newly learnt things into long-term memory. All they knew was that for long-term storage, memories move from the hippocampus, one of the oldest regions of the brain, to the neocortex, the grey matter covering the hippocampus. This, they knew, occurred during deep, dreamless sleep.

All along, nearly for a generation, scientists thought that the hippocampus pushes the memory meant for long-term storage, or consolidation, to the neocortex. But Brown University scientist Mayank Mehta (who completed his doctoral studies from the Indian Institute of Science, Bangalore, and worked for a few years in quantum physics before moving to the US and neuroscience) and his colleagues recently proved this wrong. Their work, published in the November 2006 issue of Nature Neuroscience, showed that it is not the hippocampus that uploads information to the neocortex in a burst of brain cell communication but the neocortex that drives the dialogue.

To strike up a conversation between the hippocampus and the neocortex, the neurons from both the brain regions should be in sync. In other words, if the neocortical neurons display any activity, there should be corresponding firing among the hippocampal neurons. The previous studies failed to exhibit any such synchronous firing   which neuroscientists call phase locking  in the two regions. While neocortical neurons showed rhythmic activity during deep sleep, excitatory neurons in the hippocampus showed erratic activity.

What set Mehta thinking was that if these two parts of the brain talk during deep sleep, why didn’t they appear to be speaking the same language?

There were many reasons why scientists were unable to establish this link. One reason is that they were looking at the excitatory neurons in the hippocampus. Second, they were looking at the activity using extracellular electrodes where they can only measure the spiking activity (the rush of neurons),   Mehta told.

Mehta and his colleagues demonstrated that neurons from the neocortex work in tandem not with excitatory hippocampal neurons but what they call interneurons    inhibitory brain cells in the hippocampus. The study conducted in rats hence showed that the timing of activity or talk was the same in both the brain regions, with a small delay in the hippocampus    as if the inhibitory neurons in the hippocampus were echoing the speech in the neocortex.

What really helped Mehta to crack the mystery was his association with Nobel prize-winning German scientist Bert Sakmann. Mehta’s team used a ground breaking single-cell recording technique developed at Sakman’s laboratory at the Max Plank Institute for Medical Research in Heidelberg for recording electrical activity in rats   brains.   This technique has helped us in simultaneous measurement of electrical potential in single neurons from the hippocampus and the neocortex, Sakmann, who was in Delhi earlier this month for an Indo-EU science conference, told KnowHow.   This is by far the best technique available to accurately record electric activity of individual neurons,   Sakmann claims.

“The technique of looking inside a neuron and identifying the neural type was very important for the study. If you don’t differentiate which neuron you are recording from, it all seems like a mess,  says Mehta.

Sumantra Chattarji at the Bangalore-based National Centre for Biological Sciences admits that scientists knew the hippocampus records episodic memory whereas the neocortex plays a critical role in long-term memory storage. But they haven’t been able to get the correlation correct.   The new technique made all the difference,  says Chattarji.

This method of experimentally seeing how the two brain regions “talk” to each other may help them study other aspects of brain function such as perception and emotion, hopes Mehta.

Source:The Telegraph (Kolkata,India)

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Antibiotics are often prescribed for treatment of bronchitis, but they are mostly useless, since nearly all cases of bronchitis are caused by viruses, not bacteria. A new review published in the New England Journal of Medicine finds that 70 to 80 percent of people with bronchitis are still prescribed antibiotics, which means they may get side effects like abdominal pain, diarrhea and rashes without getting any benefit from the medication. Furthermore, reviewers from Virginia Commonwealth University find that nearly 100 percent of bronchitis patients received a prescription for cough medication, despite the fact that cough medications are also ineffective for bronchitis. Most cases of bronchitis clear up easily in a few days, but people with high fevers, especially those that persist more than a day or two, should consult a doctor.

Source:ABC News